1. Field of the Invention
The invention relates generally to puzzles. More specifically, the invention relates to substantially spherical puzzles with multiple moving pieces.
2. Description of Related Art
Puzzles provide a means for individuals to test a wide variety of skills. Those that are highly complex tax both the intellectual and the creative forces, as well as make use of the solver's problem-solving skills, aptitudes in finger dexterity, and structural visualization. Those that are less complex still provide a period of fun and entertainment as the player attempts to move toward the solution.
The most famous puzzle is the RUBIK'S CUBE, which enjoyed tremendous commercial success. However, it had certain shortcomings, one of which was the relative difficulty with which the cubes moved. Movement of the different cube pieces often became tight, stubborn, or jammed up. Since the release of the RUBIK'S CUBE, a number of more spherical puzzles have appeared. Examples of these appear in U.S. Pat. Nos. 4,625,967, 4,889,340, 5,074,562, 5,389,063, 5,452,895, 5,566,941, 5,836,584, D269,629, and D283,523. Foreign publications showing examples of more spherical puzzles include PCT/JP81/00225 (WO 82/01322) and European Publication No. 0573621.
Based on the disclosures in these patents and publications, it appears that at least some of these more spherical puzzles—such as those appearing in U.S. Pat. Nos. 4,889,340, 5,074,562, 5,389,063, 5,452,895, 5,566,941, and 5,836,584—also suffer from the shortcoming associated with non-smooth puzzle piece movement. While the puzzles are designed such that the puzzle pieces have defined tracks in which they move, if the puzzle pieces do not stop precisely in the right position at the intersections of the circumferential tracks, movement of all the puzzle pieces in an entire track cannot be made until the mis-aligned piece is properly positioned. Further, it is not clear that movement of the pieces of these puzzles within their respective tracks would be smooth in practice.